Air velocity responsive snap action switch



June 22, 1954 P. L. SCHNEIDER AIR VELOCITY RESPONSIVE SNAP ACTION SWITCH Filed Jan.

Patented June 22, 1954 SWIT 4 Paul L. Schneider, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application January 13, 1950, Serial'No. 138,317

' This invention relates to a system of controls fora plurality of sounding signals for use on automotive vehicles.

,It is an object of the present invention to provide a system of control for a pair of horns orflsounding, signals which is normally conditioned ,so that only one of the signals can be sounded when the vehicle is traveling below a certain speed suitable for city driving or when atrest. When the automobile speed attains a certain value higher than permissible for city driving all signals will be sounded whenever the horn button is pressed to close a circuit.

In the disclosed embodiment of the invention, the object is obtained by use of an automatic switch which is responsive to the motion of the vehicle moving at a certain speed above that permissible for city driving or when the engine is accelerated when vehicle is at rest. When the vehicle is traveling at a speed over 35 miles an hour this automatic switch will close to condition a relay which becomes effective to connect a source of current with all horns when the push button switch is pressed to its closed position. When the vehicle is stationary and not accelerated or when the vehicle is moving below 35 miles per hour the automatic switch is opened The single figure of the drawing is a wiring diagram of the invention.

A generator Ill driven by the engine is connected by a wire II, a cut-out relay I2 and a wirel3 with a battery l4 grounded at I5. A born or warning signal E6 of low volume for city driving and a born or warning signal H for country driving is connected with the battery or current source. The horn I6 is connected with the battery [4 by a wire l8 connected with a leaf spring l9 of horn relay 2|]. The leaf spring 19 carries a contact 2| normally separated from stationary contact 22. The leaf spring I9 is attracted by an electromagnet including a core 23 and a coil 24 having one end connected to a terminal 25 which supports one end of the leaf spring IS. The circuit of the coil .24 is controlled by a control switch or horn button. 26 comprising stationary contact 2'! connected with the coil 24 and a contact 28 which is grounded. A movable contact 29 of the switch is held away from the contacts 27, 28 by a spring 38. When the movable contact 29 is moved into engagement with contacts 21, 28

3 Claims. (Cl. 20081.9)

the relay coil 24 is energized to attract leaf spring It to close relay contacts 2|, 22 in order that the low volume horn may be connected with the battery through a wire 3! connected with contact 22 and a wire 32 connected to a terminal of the horn It. The other terminal of horn l 6 is grounded.

Wire 32 is connected also with a terminal 33 of relay 34 having a core 35 surrounded by a coil 36, one end of coil 36 is connected with terminal 33. A spring blade 31 fixed to the terminal 33 carries a contact 38 engageable with a contact 39 and connected with a terminal of a country horn ll. The other terminal of horn I7 is grounded.

The other end of the coil 36 of relay 34 is connected by a lead 36a with a terminal 4| of a switch unit 38. The switch unit 40 includes a sheet metal base 42 having a flange 43 against which the periphery of a diaphragm 44 is clamped by a flange 45 of a cover 46. A pipe or conduit 4'! connects the cover 46 with a funnel or scoop 48 which receives a blast of air directed from the engine cooling fan 49. mounted on a 3 shaft 50 and driven by the engine. 7 The base 42 has a central bushing 5 l for guiding a rod 52 having an enlarged portion to provide a shoulder 53 against which a washer 54, a plate 55, the diaphragm 44, and a washer 58 are urged by riveting over at 51 the upper end of rod 52. A plate 59 attached to the base 42 provides a bracket so for supporting a pin 61 upon which a lever 62 is pivoted. The lever 62 has an extension 53 to which one end of a spring 64 is connected. The other end of the spring 64 is connected to an extension 65 of the plate 59. The spring 64 urges the lever 52 counterclockwise into engagement with rod 52 and rod 52 is urged upwardly as viewed in the drawing, said motion being stopped by virtue of engagement of diaphragm 44 with the cover 56 at the surface 46s.

The pin Bl also provides a pivotal support for a lever 56 carrying a contact 51 normally separated from a contact 68 supported by a bracket 69 electrically connected with a bracket It into which the terminal screw 4! is threaded. Brackets 59 and 10 are supported by the base 42 but are insulated therefrom. A U-shaped spring H is connected with levers 62 and 66 and normally biases lever 66 clockwise so that it normally engages a nonconducting stop 72 supported by bracket 10. Therefore, the contact 61 is normally separated from contact 68.

The edges of plate 59, attached to base 42, are surrounded by the edges of the sides of cover 13 which is retained by the screw 4| which is insulated from the cover 13 by insulation 74. The

cover 33 is not. hermetically sealed against the base A2. A vent 42a in base 42 is relatively small so as to retard air flow as the diaphragm moves thereby minimizing the surging action of the switch.

For normal city driving, the circuit is in the condition shown in the drawing. Assuming that the legal city speed limit is around 35 miles an hour, the pressure above the diaphragm? M chtained by the rotation of the engine cooling fan 49 is not sufiicient to overcome the spring 64. Therefore, when the push button 26 ismoved'to'cause contact 29 to bridge contacts 2'! and 28 the cur rent source will be connected with the low volume horn Hi to give a signal enduring solong' as the" button is depressed but the horn [1 of high volume. will not be connected with the source. When driving at 40 miles per hour or greater, or. when.

the engine is accelerated to cause-the" fan to rotate at a speed such as to cause the pressure nal 33, coil 36, lead 36a, terminal 41,, bracket 10;.

bracket 69, contacts 68, 61, lever 68 and switch base 42 which is grounded. When the coil36 has been energized, the core 35 will attract leaf spring 31 to move contact 38 into engagement with contact 39 and the horn I! will receive current from the source as will horn I6. When the speed of the engine falls to 35 milesanhour or lower such that the air pressure in duct 48 is insuflicient. to maintain the proper circulation through the duct, the switch in unit 3:! will open thereby rendering relay magnet coil 36 ineffective to attract leaf spring 31 to close. contacts 38, 39 when the push button 26 switch is closed.

Although the invention has been described as having the pipe or conduit 41 leading from the diaphragm chamber of the switch unit 46 and projecting into the funnel or scoop 48 which re-' shape, size. and arrangement of parts may, be made so that. the conduit 41 would be in any'air; stream which produces sufficient pressure to operate the diaphragm of the switch unit 40.

While the embodiment of the present invention as herein disc1osed,,constitutes a preferredform, it is to be understood that otherforms might be adopted.

What is claimed is-as follows:

1. An'air velocity responsive, snap action switch, comprising in combination, a stationary contact; amovable arm supporting a contact, a second movable arm, each arm'having one end pivotally mounted on a common axis; a snap spring interconnecting the free ends of the arms; a coiled spring having one end connected to a stationary part and having its other end connected to the second lever to. move it in one direction so that the center line of action of the ends of the snap spring is below the axis of the levers to holdnormally the contacts separated; .an air collecting duct; a compact tube positioned within the duct;

a chamber connected with said tube and parti-" tioned into two compartments by an air impervi- When. that happens the ous diaphragm; an operating rod carried by the diaphragm and engaging the second arm, said rod acting upon said second arm, when the velocity of air in said tube reaches a predetermined value, to move same against the action of the coiledsprin'g to move" the center line of action of the ends of the snap spring above the axes of the arms whereupon the first arm is biased to cause the. contact to engage the stationary contact.

2. An airvelocity responsive snap action switch, comprising in combination; a stationary contact; a movable arm supporting a contact, a second movable arm, each arm having one end pivotally mounted on a common axis; a snap spring interconnecting the free ends of the arms; a coiled spring having one. end connected to a stationary, part and having its other end'connectedto the. second lever to move it in one direction so, that the center line of action of the ends of the snap. spring is below the axis of the levers to. holdliiormally the'contactsseparated; an air. collecting. duct; a compact tube positioned withinthe. duct;

a diaphragm movable in one direction inresponse to pressure increase in the tube; a plungeractu ated by the diaphragm. andengageablewith the. second arm to move it in a directionagainst the.

force of the coiled spring to move thecenter line of action of the ends of the snap spring above the axes of thearms whereupon the first arm is.

movedwith a snap action to causeits contact to engage the stationary contact, said coiled spring,- being operable, when the pressure in the-tube is 3. An air actuated switch comprising in combination; a stationary contact; a first levercarrying a contact adapted to engage; the stationary contact; a second lever having an angular. leg,

said-levers being pivotally mounted on a common axis,.said levers having opposed abutments adja cent their free ends; a U-shapedsnap springhavingopposite ends'operatively connected witlrthex.

abutments and adapted to shift the center line of; actionof the ends of the snap spring on: either side of. the axes of the levers; resilient meanshav ing' one end connected to the leg of the second lever, saidresilient meansbeingzoperable to urge: the; second, lever. in one direction so that center" line of action of the ends of the leaf springis, on one side of the axes of the levers to separate. the contacts; an air conducting duct, a chamber ad jacent the duct; an air impact tube connected with the duct and thechamber; a diaphragmmovable in one direction in response to pressure in saiditube; an operating-rod carried by the diaphragmand engaging the second leverand=operable-to movesaid' second lever in response to movement of the diaphragm in said one direc tion to cause the center line of the ends of the snap spring'to shift to the other side of the axesof the leversto close the contacts.

References Cited in the file of this patent UNITED STATES PATENTS 

